Accretion definition, an increase by natural growth or by gradual external addition; growth in size or extent. See more.
Alveoli are tiny sacs within our lungs that allow oxygen and carbon dioxide to move between the lungs and bloodstream. Learn more about how they function and quiz your knowledge at the end.
Conclusion Questions 3.3.1 1. The walls of the alveoli in the lungs are incredibly thin. Explain how this structure is related to function in the body. The walls of the alveoli are extremely thin so that they can serve their purpose of allowing diffusion of oxygen and carbon dioxide to happen. This is where gas exchange occurs.